Conventionally, in the work vehicle, there has been a structure in which work equipments are provided in front of and at the rear of a vehicle body such that a blade apparatus and a ripper apparatus are respectively provided in front of the work vehicle and at the rear of the work vehicle, for example, a bulldozer. In the case of moving forward, working by using the front work equipment or the like, it is advantageous in view of visibility, safety, operability and the like that the operator drives the vehicle in a state of viewing straightly forward with respect to the vehicle. However, in the case of moving backward, working by using the rear work equipment or the like, it is necessary for the operator to view the rearward portion and the rear work equipment. It causes a very large pain and a great fatigue for the operator to view rearward in a state of keeping an attitude that the operator views straightly forward, since it is necessary for the operator to twist the body at a degree more than the necessity.
In order to improve the disadvantage mentioned above, there has been conventionally suggested some techniques.
As a prior art of a driver's seat apparatus for a construction machine, for example, there is a structure in which only an operator seat in the bulldozer is made rotatable as shown in FIG. 12. FIG. 12 is an upward elevational view of the driver's seat apparatus.
In FIG. 12, an operator seat 11 provided in a rear portion of a substantially center of a driver's room 3 is structured such as to freely rotate around a center of rotation N in a lateral direction, and a first control console 31 which is mounted to a floor frame 20 is provided in a left side of the operator seat 11. A left arm rest 32 is provided in an inner side on an upper surface of the first control console 31, and operating levers 33 and 34 which respectively operate a steering gear and a transmission are arranged in a front side and a left side of the left arm rest 32.
Further, a second control console 35 which is mounted to the floor frame 20 is provided in a right side of the operator seat 11, a right arm rest 36 is provided in an inner side on an upper surface of the second control console 35, and operating levers 37 and 38 which respectively operate a front work equipment (a blade) and a rear work equipment (a ripper) are arranged in a front side and a right side of the right arm rest 36.
When the vehicle travels forward and works by using the front work equipment (the blade), the structure is made such as to direct the operator seat 11 to a straightly forward direction so as to fix. Then, in the case of the forward travel, the operating levers 33 and 34 are operated so that the vehicle moves forward, and in the case of the blade work, the operating lever 37 is further operated.
Further, when the vehicle travels backward and works by using the rear work equipment (the ripper), the structure is made such as to rotate the operator seat 11 at a predetermined angle .gamma. in a rightward direction so as to direct it to an obliquely right front direction and fix. Then, in the case of the backward travel, the operating levers 33 and 34 are operated so that the vehicle moves backward, and in the case of the ripper work, the operating levers 33 and 34 are operated so that the vehicle moves forward and the operating lever 38 is further operated so as to vertically move the ripper.
Accordingly, since the operator seat 11 is rotated at the predetermined angle .gamma. and is fixed in an obliquely forward direction when the vehicle travels backward and works by using the rear work equipment (the ripper), it is not necessary for the operator to forcibly twist the body and a fatigue of the operator is reduced.
However, the operating levers 33 and 34 which operate the steering gear and the transmission are maintained to be fixed at a position suitable for the vehicle to travel forward.
Further, as the other prior art, there is, for example, a technique concerning a driver's seat of a work vehicle which is disclosed in Unexamined Japanese Patent Publication No. 10-131235. In the publication, as shown in FIG. 13, a travel operating lever 44 which controls a speed change and a steering angle and a work equipment operating lever 45 which drives a work equipment are respectively provided on arm rests 42 and 43 which are provided in left and right portions of a seat 41. Further, an accelerator pedal 47 and a brake pedal 48 are provided on a step 46 which is attached to a front end of a seat mounting plate on which the seat 41 is mounted, and the operating levers and the pedals mentioned above are vertically moved together with the seat 41 by means of ascending and descending means (not shown) provided below the seat 41, and can move in a longitudinal direction. Further, each of the operating levers 44 and 45 can be adjusted in the longitudinal direction by operating an operating lever longitudinally adjusting knob 49, and each of the operating pedals 47 and 48 can be adjusted in the vertical direction and the longitudinal direction by operating a pedal vertically adjusting knob 50 and a pedal longitudinally adjusting knob 51, respectively.
However, in the conventional technique concerning the driver's seat of the work vehicle mentioned above, there are the following problems.
In the case of the work vehicle such as the bulldozer, it is necessary to perform the operation of the travelling system (the forward and backward movement, the speed change, the steering angle and the like) for the vehicle substantially at the same time as the time of using the rear work equipment. However, in the technique shown in FIG. 12, in the case of travelling backward and operating the rear work equipment, it is possible to fix the seat at a position of directing the seat to an obliquely forward direction, however, the operating lever for the travelling system is fixed so as to align with the direction of the forward movement, so that it is impossible to set to the oblique position in the same manner as that of the seat. Accordingly, in the case of travelling backward and operating the rear work equipment, the operator can not secure the optimum position of the operating lever for the travelling system, so that there is a problem that an operability is bad.
Further, in the technique disclosed in Unexamined Japanese Patent Publication No. 10-131235 mentioned above, since the structure is made such that the various kinds of operating levers and the various kinds of pedals are integrally provided with the seat so as to be rotated together with the seat, thereby adjusting the position, an outer size of the driver's seat is increased. Accordingly, in the case of maintaining equipment (various kinds of main valves for a steering gear, a work equipment and the like) disposed below the driver's seat, since it is impossible to take out the driver's seat from the driver's room, it is necessary to disassemble the driver's seat within the driver's room, so that there is a problem that a lot of maintenance labor and cost are required. Further, since the driver's seat becomes a special product, there is a problem that it is hard to employ a standard product on market and a cost is increased.